Draw mechanism for straight bar-knitting machines

ABSTRACT

A straight-bar knitting machine including an asymmetric center differential unit incorporated into the gearing system conveying from a variable linear draw mechanism normal reciprocatory movements to the carrier drive and the slur drive rack. This unit is operable from the selvedge screws so to adjust the carrier and slur drives that traverses thereof are asymmetric with respect to centerlines of the knitting heads, and the central points of these traverses are maintained coincident with centers of knitting widths. A draw shortening differential unit, associated with the draw mechanism and also operable from the selvedge screws, minimizes the constant overtravel of the slur cams beyond the yarn carriers.

United States Patent Richter [72] Inventors Barry F. Swanwick 2,063,000 1936 66/ 126 Melton Mowbray; 2,705,879 I955 Scheller... 66/ 126 Ernest West, Kirkby in Ashfield; Leslie 2,764,007 1956 Monk 66/126 Collins, Cropwell Butler; Ernest Chambers, 2,872,798 1959 Matthews et al 66/126X Stapleford, England 3,073,l38 I963 Blood 66/1 10 2 1 1969 3,400,560 1968 Start et al. 66/ I I0 I 6 ar. [45] Patented Apr. 13, 1971 FOREIGNPATENTS [73] Assignee S, A. M k Li i 1,014,27l 1957 Germany 66/126 sutmndmAshfield Nottinghamsifire 1,435,330 I966 France 66/126 England 742,650 1955 Great Britain 66/126 Priority Mar. 2 Great Britain [33] Great Britain Primary Examiner-Ronald Feldbaum [3 l 1 13911/68 Attvrney--Larson, Taylor and Hinds [54] DRAW MECHANISM FOR STRAIGHT ABSTRAQT: A straight-bar knitting machine including an KNHTING MACHINES asymmetric centerdifierentlal unit incorporated mto the gear- 12 Claims, 8 Drawing Figs mg system conveying from a variable linear draw mechanism normal reciprocatory movements to the carrier drive and the [52] US. Cl 66/126 h d -i k Thi u it i o erable from the selvedge crews lllt- Cl D04) 15/52 so to adjust the carrier and slur drives that traverses thereof [50] Field Of Search 66/126- are asymmetric with espect to cemeflineg of the knitting heads, and the central points of these traverses are maintained coincident with centers of knitting widths. A draw shortening [56] References cued differential unit, associated with the draw mechanism and also UNITED STATES PATENTS operable from the selvedge screws, minimizes the constant 2,022,468 1935 Hug 66/126 overtravel of the slur cams beyond the yarn carriers.

Panama A ril 13, 1911 1 3,575,011

7 Sheets-Sheet 1 [H5 I RHS Fla. 7.

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c i 7 -Asa 0 I Patented 1 April 13, 1971 7 Sheets-Sheet 2 Patentd April 13, 1971 7 Sheets-Sheet 5 Patented April 13, 1911 3,575,017

'7 Sheets-Sheet 4 Patented April 13, 1971 7 Sheets-Sheet 5 Patented A ril 13; i-i1 7 f 3,515,017

7 Sheets-Sheet 6 DRAW ll/lElSM FOR SGHT BAR-KNITTHNG MACHINES This invention appertains to a draw motion for a multihead straight-bar knitting machine of the Cottons Patent orsimilar type for fully-fashioned garment manufacture.

in a machine of the type concerned, slur cams, one to each head or division, are mounted on slur cam boxes fastened to a tie bar which extends along the length of the machine and thereby couples the slur cam boxes together. Thus, driven from the main draw mechanism, the tie bar drives the slur cams across the sinker heads at the divisions. The said tie bar is associated with a fixed slur bar or rail which, in the case of a machine fitted, as isthe machine to which the invention is applied, with a variable draw, is mounted on small levers to enable the said slur cams to be retracted from the rear of the sinker heads during the knitting part of the loop-forming cycle.

Associated with the slur cams which, together with sinkcrs they operate, perform the yarn sinking function, are rods which extend the length of the machine and upon which are mounted yarn carriers, at least one to each sinker head. The requirement is that a selected carrier rod shall synchronously reciprocate with the slur cams on all knitting widths but with a controlled lead of the said carriers over the slur cams.

The invention is primarily intended for application to a machine having a chain type of yarn carrier drive combined with means to give the necessary controlled lead of the yarn carriers ahead of the slur cams during each traverse. It is, however, also possible to apply the invention to a machine equipped with a friction type of yarn carrier drive, as will be hereinafter more fully described.

The invention, moreover, has reference exclusively to a multihead straight-bar knitting machine of the type specified including any appropriate means for shaping knitted fabric or garment blanks produced at the divisions. Preferably, in this regard, the machine includes fashioning mechanism for widening or/and narrowing by loop transference to increase or decrease the number of wales, such increase or decrease being brought about by increasing or decreasing the number of operative needles at either or both selvedges without alteration to the character of the stitch. In this case, the increase or decrease in the knitting width is controlled by the conventional LH. and RH. selvedge screws which are indexed according to a machine control system capable of being programmed according to the gannent shape specification. These selvedge screws limit the traverse of the yarn carrier rods, but controlled deceleration is essential to minimize or prevent impact and rebound when the rods contact stops carried by nut housings on the selvedge screws. Similarly, these selvedge screws also effectively vary the traverse of the slur cams according to the knitting width by means of the proportional movement of die blocks in a reciprocating linkage actuated from a draw motion, e.g. of the kind in which a rotary draw cam, operating on trucks mounted on a pitman to cause to and fro movement of the latter, is used to effect, through the medium of a swinging lever system and associated transmission, variable reciprocating motion to the slur cams and carriers.

As is well known to those acquainted with the art concerned, a straight-bar knitting machine of the type referred to is provided with a continuously rotatable cam shaft from and by which the various machine motions are respectively derived and controlled. From this camshaft is driven, usually through the medium of 2:1 bevel gearing, a cross shaft upon which is secured the aforementioned rotary draw cam.

in a machine equipped with fashioning mechanism as aforesaid, the cam shaft is adapted to be axially shifted bodily by a longitudinal shagging motion, from a normal position during which yarn sinking and knitting takes place to another position in which fashioning cams are introduced to the various motions for garment shaping.

Heretofore, the variable draw traverse has usually been controlled from one selvedge screw, commonly the Lil. screw, and the slur traverse has always been symmetrical about the centerline of the knitting head. This is not ideal for the manufacture of asymmetrical garment pieces (as, for example, cardigan fronts) which can be produced by disconnecting the variable linkage and locking on a fixed constant width. Asymmetrical traverses of yarn carriers are possible when using a chain type carrier drive which conveniently incorporates a combined escapement and decelerating means; they are also possible when using friction drives which latter, however, have the disadvantage of impacting at the terminal positions and also, when heavy masses are involved, of limiting the speed of the machine. Due to the excessive slur traverse beyond the required knitting width the production of asymmetrical garment pieces has heretofore been wasteful in terms of machine time.

The object of the present invention is to provide, in a multihead straight-bar knitting machine of the type herein referred to, an improved draw mechanism such that the over travel of the slur cam beyond the selvedge positions of the carrier at each head or division is a substantially constant and minimum amount for all knitting widths between two selvedges, irrespective of the shape of the garment piece. The proposed improved system caters for the production of garment pieces knitted symmetrically or asymmetrically and ensures at all times that the center of the slur cam travel substantially coincides with the centerline of the garment piece being knitted.

According to this invention there is provided a multihead straight-bar knitting machine of the type concerned, characterized in that there is associated with the gearing system adapted to convey from the draw mechanism the normal reciprocating movements both to the carrier drive and to the slur drive rack simultaneously a differential movement-transmitting mechanism (hereinafter for convenience called the asymmetric center differential unit) which is operable from the L.H. and RH. selvedge screws to adjust the carrier and slur drives so that the varying carrier and slur traverse are asymmetric with respect to the centerlines of the knitting heads, the operation of the said differential being such as to maintain the center points of these traverses substantially coincident with the centers of the varying knitting widths, i.e. the median lines of the garment pieces being knitted.

in a convenient embodiment of the invention the aforesaid gearing system includes a pinion in mesh with a rack arranged to be reciprocated by the draw mechanism, and the asymmetric center differential unit, when operated from the two selvedge screws, algebraically combined the axial movements of the two nut housings mounted on these screws suchwise as either to laterally displace or to leave undisturbed the rotational axis of the pinion, according to garment shaping requirements, any such lateral displacement of the said axis effected by rotation of either selvedge screw being proportional to one-half of the axial distance moved by the nut housing along that screw.

A practical form of the improved machine includes, in association with the draw motion, a second differential mechanism, also operable from both selvedge screws, for the purpose of so shortening the to and fro movements of the draw bar as to minimize the overtravel of the slur cams beyond the selvedge positions of the yarn carriers.

Preferably, the variable draw mechanism is a linear one so that there shall be at all knitting widths a substantially constant overtravel of the slur cam traverse with respect to the yarn carrier travel. in this connection, the trucks upon which the rotary draw cam operates may be mounted upon a slidable draw pitrnan of bar form which is linked with pitman quadrants having engaged therein die blocks which are mounted on a fulcrummed main draw lever arranged to impart movement to a draw bar. In such an arrangement the action of the draw cam upon the trucks simply moves the pitman to and fro in a straight line, similar proportional movements also being imparted to the draw bar.

The output from such a linear draw mechanism is, in accordance with this invention, affected by varying the position of a variable draw die block center, this position being controlled by the output from the draw shortening differential mechanism which algebraically summates the combined movements of the two selvedge screws. The arrangement provides what is, in effect, an infinitely variable ratio gear and lever system whereby a constant movement from the draw cam can be varied to impart a substantially constant overtravel of the slur cams as just described.

It is, however, also possible to apply the principles of the invention to a more conventional variable draw mechanism producing varying overtravel of the slur cams beyond the knitting width, in which instance a draw shortening differential mechanism may conveniently be incorporated into the draw control shaft by means of which the motion of the L.H. selvedge screw is conventionally conveyed to a lead screw with which the main draw lever is furnished. As known to those skilled in the art, this draw control shaft is the one which at one end is drivingly connected with the L.H. selvedge screw by a chain passed around two sprocket wheels, and at the other end has secured thereto a bevel gear arranged in mesh with a companion bevel gear from which motion is conveyed to the draw lever lead screw through a universal joint. Accordingly, in the last mentioned arrangement the output from the draw shortening differential mechanism is to the said bevel gearing.

The asymmetric center differential unit may be of the worm and wormwheel type. Any other appropriate form of such a unit may, however, be employed. For example, the said unit may be based on racks and pinions, or on a spur gear or a bevel gear system. The form of the draw shortening differential mechanism may also vary, according to requirements.

In order that the invention may be more clearly understood and readily carried into practical effect, a comparison between a symmetrical garment piece and asymmetrical garment pieces, and specific constructional examples of the related asymmetrical center and draw shortening differential units constituting this invention will now be described with reference to the accompanying purely diagrammatic drawings, wherein:

FIG. 1 comprises the said symmetrical garment piece shown in relation to the centerline of a knitting head of a multihead straight-bar knitting machine and two asymmetrical garment pieces shown in relation to the centerline of slur travel and knitting width;

FIGS. 2 and 2A together constitute an elevational view, from the rear of such a machine equipped with a chain-type carrier drive, illustrating the related asymmetrical center and draw shortening differential units in association with a linear draw mechanism;

FIG. 3 is a plan view as seen in the direction of the arrow A in FIG. 2 of the asymmetric drives for effecting simultaneous adjustments both of a carrier drive roller and also of a slur cam longitudinally in relation to a sinker head, determined from the L.H. and RH. selvedge screws;

FIG. 4 is a detail perspective view, partly in section, of the asymmetrical center differential unit, per se;

FIG. 5 is a detail perspective view, as seen from the front of the machine, illustrating a lead changeover mechanism which is necessary when employing a chain-type carrier drive;

FIG. 6 is a diagram showing the manner in which two identical sleeves can be produced on each knitting head of the illustrated machineutilizing the asymmetrical centering system influenced from the selvedge screws; and

FIG. 7 is a detail cross-sectional view depicting primary and secondary tie bars which respectively couple together primary and secondary sets of slur boxes and cams and are themselves adapted to be latched together during the knitting of two identical sleeves on each knitting head.

Like parts are designated by similar reference characters throughout the drawings.

In FIG. 1, the two parallel vertical chain dotted lines LHS and RHS respectively represent, in diagrammatic fashion, lefthand and right-hand extreme selvedge positions. The median line CL is the centerline of a knitting head. At a is depicted a symmetrical garment piece 86. At C and SC are respectively represented the carrier and the slur cam at the knitting head. One of the varying knitting widths of this garment piece is designated KW, each such width extending to equal extents at opposite sides of the centerline CL-as to which see the two equal dimensions KW and KW The controlled lead of the carrier C over the slur cam SC is shown at L, whereas the chain lines 0 and 0 represent the substantially constant overtravel of the slur cam SC beyond the left-hand and right-hand selvedge positions of the carrier C. In this case, moreover, the slur traverse ST is symmetrical with respect to CL.

At b in FIG. 1 is shown as asymmetrical garment piece ASG which is a left-hand piece inasmuch as it is knitted principally to the left of CL. Similarly, at c in FIG. 1 there is shown a right-hand asymmetrical garment piece ASG knitted principally to the right of CL. It will be seen that in each of these last two cases the slur traverse ST, instead of being symmetrical with respect to the centerline CL of the knitting head, as it would previously have had to be, is, in accordance with the present invention, off-centered suchwise as to have a centerline SCL which is still coincident with the centerline of the knitting width KW of the shaped piece. This enables the overtravel 0 and O of the slur cam SC beyond the selvedge positions of the carrier C to be a substantially constant and minimum amount at all knitting widths between the selvedgeshowever irregular the shape of the garment piece.

These desirable results are achieved by the combined differential mechanisms presently to be described with reference to FIGS. 2, 2A, 3, 4 and 5.

The multihead straight-bar knitting machine to which these mechanisms are applied includes a L.H. axially immovable selvedge screw 1 engaged in an axially movable nut housing 2, and also a similarly mounted R.H. selvedge screw 35 engaged in a nut 41. The two nut housings 2 and 41 are connected by links and-51 with the two saddles 52 and 53 respectively of a chain-type carrier drive. As is conventional, these two saddles have mounted thereon pairs of sprocket wheels 54, 55 and 56, 57 around which is passed a carrier driving chain 58. This chain is also passed around two sprockets 23 and 59. The chain 58 is furnished with a carrier drive roller 16 arranged to act upon a carrier driving slide 60 which, as shown in FIG. 3, is connected with a carrier rod 61. In FIG. 3, a yarn carrier at one head or division is indicated at C, and the corresponding slur cam at SC, this cam being attached to a slur cam box 62 slidably mounted on a fixed slur bar or rail (not shown). The slur cam boxes are fastened in the usual way to a tie bar 63 which is common to all of the slur cams and is arranged to be driven from the variable draw mechanism DM (FIG. 2A), i.e. from the main draw lever 33 which reciprocates a draw bar 64. In this way the slur cams SC are traversed to and fro across the sinker heads at the divisions. Since the draw is a variable one, the slur bar or rail is, in accordance with known practice, pivoted on an oscillatory shaft (not shown) controlled from the main cam shaft of the machine to cause the slur cam assembly to be withdrawn from the sinker heads into an inoperative position during the actual knitting part of the loop-forming cycle.

Carrier stops (not shown) are fitted to the machine and operated in the conventional manner from the selvedge screws to ensure the correct locations of the yarn carriers at the ends of their traverses across the sinker heads.

The linear draw mechanism DM with which the illustrated machine is equipped comprises a draw cam 65 which is rigidly mounted on the conventional cross shaft 66, and operates on trucks 67 and 68 mounted on a slidable pitman bar 69. The cam 65 drives the pitman bar 69 to and fro between spaced bearing brackets 70 and 71 attached to the machine frame. The pitman bar 69 is connected, by means of a link 72, to pitman quadrants 34 which are fulcrummed at 34a. The pivotal center of a die block 32 mounted on the main draw lever 33 is adjustable in slots in the pitman quadrant 34 to vary the lever 23 turnable, as required, about a pivot 29 on swinging link 29a pivoted about center 29b in a fixed bracket 73.

The lever 23 is tumable upwardly, at required times, to shorten the draw by the vertical upward movement of a nut housing 27 constituting a component of a draw shortening differential unitgenerally designated by the letters DSU (see FIG. 2A). The outer end of the lever 28 is connected by a link i 30 with the nut housing 27. Thus, in the described linear draw mechanism DM the output thereof is affected by varying the position of the center of the die block 32, and, in accordance with a characteristic feature of this invention, this position is controlled by the output from the draw shortening differential runit DSU which algebraically combined, e.g. summates, the

movements of both nut housings 2 and '41 upon rotation of'the sclvedge screws 1 and 35 in the manner hereinafter to be described. The purpose of successive and varying draw shortenings is to ensure a minimum as well as a substantially constant overtravel of the slur cams beyond the selvedge positions zzthereby obviating any waste movements of these cams.

Meanwhile it will be convenient to describe the asymmetrical center differential unit, generally designated by the letters ADU, and by means of which additional longitudinal displacements are imparted both to the conventional slur drive rack attached to the slur tie bar 63 and also to the carrier drive roller to, thereby off-centering the slur and carrier drives in accordance with the positionsof the and RH. selvedge screws H and 35. Thus it is that the difi'e'rentialunit' ADU is Iadapted to centralize the slur traverse ST about the median line of the garment piece being knitted. r, The said asymmetrical center differential unit ADU com- :prises Lll-ll. and RH. worms 8 and It) respectively which, as shown in FIGS. 2, 3 and 4, are disposed parallel to one another with a worm wheel 9 being freely centeredin a slipper Ill and "interposed between the worms 8 and i0 and intermeshed with both. Slipper 11 is freely slidable upon and along both wonns "h and it! and has therein coaxial upper and lower bearings in which is mounted a vertical transmission shaft 9a. Upon the lower end of the shaft 90 is rigidly secured spur pinion t2 which is arranged to mesh with the rack 13 connected with the draw bar 64. The upper endof the shaft 9a projects through the top of the slipper ill and has rigidly secured thereto the bevel gear 114 from which the carrier and slur drives are conveniently derived. The bevel gear ll iis arranged in mesh with a. bevel gear 17. The last mentioned gear is adapted to rotate, but is axially slidable along, a splined shaft llfl which, through ithe medium of a further pair of interrneshed bevel gears 19 and 20, is driveably connected with a shaft 211. Upon the shaft 2-! are secured chain sprockets 22 and 23 around'which are respectively passed the slur-draw chain 74 and the carrier driving chain 55. A torque limiter 75 is provided between the bevel gear 19 and the splined shaft 18. i g

: Longitudinal movement of the chain 74'is transmitted to the slur drive rack 15 through the medium of a chain sprocket 76 which is secured upon one end of a shaft 77 to the opposite end of which is secured a spur pinion 78 arranged in mesh with the said rackall as illustrated in FIG. 3. The shaft 77 is 'rnounted to turn in a bosslike bearing block 79 which is connected, through the medium of a link 80, with a previously proposed fonn of lead changeover mechanism diagrammatically depicted at LCM in H0. 3. Since the carrier driving means in the illustrated machine are of the chain type, some automatically operable lead changeover means are necessary to r eversethe controlled lead of each yarn carrier C over the corresponding slur carn SC at each reversal of the traverse of the said slur cam across the relevant sinker head. The particular lead changeover mechanism LCM shown in FIG. 5 functions to shift the slur drive rack 15 an appropriate distance, in the relevant direction and relatively to the carrier driving chain 58 at each reversal of slur traverse, through the medium of the link and the pinion 78. Thus, as will be seen, the lead changeover mechanism LCM comprises a relatively long pivoted lever 81 to which the appropriate end of the link 80 is attached and a substantially shorter pivoted lever 82, the said two levers, arranged parallel to one another, being connected by a link member 83. The member 83 carriers two trucks 84 and 35 arranged in engagement with and at respectively opposite sides of a rotary lead cam 86 rigidly secured either upon the cross shaft 66 (as shown) or upon any other suitable halfspeed shaft. As the cam 86 rotates the bearing block 79 will be moved to and fro in time with the reversals of the slur traverse. At each such reversal, any displacement of the block 79 will cause the chain sprocket '76 and hence also the pinion 78 to rotate suchwise as to shift the slur drive rack 15 and thereby change over the lead.

The L.l-l. won'n 8 of the asymmetrical center differential unit ADU is arranged to be driven from the L.H. selvedge screw i via chain' sprockets 3 and 4, a chain 87 passed therearound, a shaft 5, further chain sprockets 6 and 7 having passed around them a further chain 58, and a shaft 89. On the other hand, the RH. worm 10 of this same unit is arranged to be driven from the RH. selvedge screw 35 through the medium of chain sprockets 36 and 37 having a chain 9t) passed around them, a shaft 38, a chain sprocket 39 secured upon the shaft 35, a chain sprocket 40 secured upon one end of the RH. worm 10 and a chain 91 which is passed around the said sprockets 39 and 40.

As to the construction of the draw shortening differential unit DSU this includes, as shown in FIG. 2A, a vertical R.H. screw 26 with which is engaged a nut housing 27 having integral therewith a spur gear'42 and, disposed parallel to this worm, a vertical splined shaft 46 having integral therewith a spur gear 33 arranged in mesh with the gear 42. The upper and lower ends of the screw 26 and the splined shaft do'are turnable'in bearings in upper and lower brackets 92 and 93. The screw Zti'is rotatable from the LH. selvedge screw K through the medium of a pair of intermeshed spiral gears 24 and 25 secured respectively upon the shaft 5 and the upper end of the said screw. On the other hand, the splined shaft 46 is rotatable from the RH. selvedge screw 35 via a further pair of intermeshed spiral gears 44 and 45 secured respectively upon the shaft 38 and the upper end of the said splined shaft.

For the purpose of the following further description of the operation of the herein described associated differential units, it will first be assumed that, with the linen draw mechanism DM stationary, the LH. selvedge SCl.;W ll only is turned manually. As a consequence, the nut housing 2 is displaced axially along this screw and, proportionally to the extent of the axial movement,'the L.H. worm 8 and hence also the worm wheel 9 'of the unit ADU will turn to effect a sliding movement of the slipper lll axially along both worms 8 and it). The result of this last mentioned movement is to laterally displace the axis of the spur pinion l2-longitudinally with respect to the rack 113 whichin these conditions is stationary-so that the said pinion turns about this axis to rotate the bevel gear 14. The lateral displacement of the axis of the spur pinion 12 is proportional to one-half of the longitudinal movement of the nut housing 2 caused by this manual turning of the selvedge screw 1. Through the medium of the splined shaft 18, the bevel gears 19 and 20, the shaft 21 and the sprockets 2-2 and 23 and the two chains 58 and 7d are longitudinally moved each to the same extent in the relevant direction to shift the slur drive rack 15 and the carrier drive roller 16. Rotation of the LH. selvedge screw 1 additionally and simultaneously turns the spiral gears 24 and 25 to rotate the RH. screw 26 of the unit DSU as a consequence of which the nut housing 27 is caused to move axially upwards since the gear 42 integral with that housing is that this'time held and prevented from rotation by the gear'43 integral with the stationary splined shaft 46. The lever 25 corinectedwith the nut housing 27 as hereinbefore described is accordingly swung upwardly to adjust the height of the fulcrum 31 of the main draw lever 33. In this way the quadrant die block 32 is adjusted to vary the lever ratio of the pitman quadrant 34.

lt will now be assumed that the L.H. selvedge screw 1 is sta tionary and that the R.H. selvedge screw 35 is manually rotated. This time the R.H. worm is rotated, through the sprockets 36 and 37, the shaft 38 and the sprockets 39 and 40. As a consequence, the wormwheel 9 is again rotated, but as the latter is engaged with the now stationary L.H. worm 8, the slipper 11 suitably moves axially along the worms 8 and 10 to cause rotation of the spur pinion l2 and bevel gear 14 about their common axis. This axis is thus displaced laterally (since the rack 13 is still stationary), the displacement being proportional to one-half of the longitudinal movement of the nut housing 41 caused by manual turning of the selvedge screw 35. The rotation of the pinion 12 and the bevel gear 14 effects adjustment of the carrier drive roller 16 and also of the slur cams SC longitudinally in relation to the sinker headsproportionally to the axial displacement of the nut housing 41 on the RH. selvedge screw 35.

Rotation of this RH. selvedge screw and hence also of the shaft 38 additionally and simultaneously rotates the splined shaft 46 through the spiral gears 44 and 45. The consequent rotation of the gear 42 through the medium of the rotating gear 43 again moves the nut housing 27 vertically upwards. The lever 28 is thus again caused to swing upwardly to vary the lever ratio of the pitman quadrant 34.

It will therefore be appreciated that if, as in the practical running of the machine, the L.H. selvedge screw 1 is turned at the same time as the RH. selvedge screw 35, the displacements (for draw shortening) of the main draw lever pivot center 31 and the die block 32 which are proportionate to the sum or the difference of the displacements of the said nut housings 2 and 41. Simultaneously, the positions of the yarn carriers and slur cams longitudinally in relation to the sinker heads will be adjusted by a distance which is one-half of the sum or difference of the displacements of the two selvedge nut housings 2 and 41 suchwise as to centralize the slur traverse ST about the centerline of the knitting width KW.

It will also be appreciated that since the lever ratio of the pitman quadrant 34 determines the longitudinal movement of the draw yoke 48 as a proportional part of the lift on the draw cam 65 that the traverse of the slur cam SC can be increased or decreased by a distance corresponding to the combined axial displacements of the nut housings 2 and 41 along the selvedge screws 1 and 35.

It is to be clearly understood that the rack 13 which is connected with the draw bar 64 is continuously reciprocated, during knitting to move the carrier driving chain 58 and the slurdraw chain 74 in company with one another to produce the carrier and slur cam traversein the usual way. Thus, any compounded lateral displacements of the axis of the spur pinion 12 caused by corresponding movements of the slipper 11 at a time when both of the selvedge screws 1 and 35 are racked round, result in rotation of the said pinion, in one direction or the other, additional to the rotation imparted thereto in the usual way by the draw mechanism DM. In other words, the adjustments to the carrier drive and slur draw effected by this additional rotation of the pinion 12 are superimposed upon and thus compounded with the normal to and fro movements of the chains 58 and 74. It has also been stated that any compounded displacement of the common axis of spur pinion 12 and slipper i1 is proportional to one-half of the sum or difference of the longitudinal displacement of the selvedge nut housings 2 and 41. This proportion is in fact the gear ratio between the axis of the spur pinion 12 and the final drive to the carrier rods. Thus, if this ratio is 4:1 then the lateral displacement of the axis of the spur pinion 12 will be one-eighth of the compounded displacement of the selvedge nut housings 2 and 41.

As previously mentioned, the machine may alternatively be equipped with a friction type of yarn carrier drive. In such a system a carrier rod drive box is driven direct from the tie bar and therefore travels the same distance. A selector mechanism may be provided on the drive box to select any one of a plurality of carrier rods which extend the full length of the machine. Mounted on to each carrier rod is a light weight friction box in each knitting division and to this is attached one or more yarn carriers as necessary. Stops are also provided in each division to control the traverse of the friction boxes according to the width of the garment being knitted and are connected to the selvedge screw nut housings 2 and 41 by rods extending the length of the machine so as to simultaneously vary the stop positions in each knitting division as required. Since the slur cams travel a substantially constant distance beyond the selvedge positions, the friction boxes have to slip only twice this distance and this automatically derives a constant lead of the carriers in front of the slur cams thus obviating the need for any lead changeover mechanism.

The advantage of this form of construction is that the mass of the reciprocating carrier system is minimized and that substantially reduced driving forces need be applied, thus minimizing the impact of the carriers reaching their stops at increased knitting speeds.

Alternatively a carrier drive box may be traversed directly by a rack and pinion driven rectangular bar which is directly and proportionally reciprocated by the variable draw linkage and associated gear transmission from the draw cam as previously described. In this application the deceleration of the carrier rod, which has yarn carriers fixed to it and spaced at one to each knitting division in conventional manner, as it approaches the terminal or selvedge position is determined entirely by the profile of the draw cam and the variable draw ratio relative to the width of fabric being knitted. Since there are inherent transmission and strain losses in the variable draw linkage the precise traversing of the carrier rod drive box and hence the carriers between selvedge stops cannot be accomplished direct from the draw cam and some small excess motion is essential. A relatively heavy friction interposed between the carrier and drive bar and the above mentioned rectangular bar provides a means of losing this excess traverse at the expense of a relatively small shock on the selvedge cam nut housings. At the terminal or selvedge position the friction will slip by a small amount corresponding to the excess motion less the motion lost due to linkage strain. A conventional lead changeover mechanism may be provided so that load on the selvedge screw nut housings is minimized and the above mentioned friction is confined to the small degree of slipping at the selvedge position as described. This arrangement provides a means of obviating the costly carrier chain drive whilst still accomplishing the desired degree of control of the carrier rod under all conditions of speed and asymmetry of garment shape.

Thus, as will be appreciated, combined draw shortening and symmetrical center differential units can be used with any form of carrier drive (either chain or friction) provided that means are employed to ensure the necessary lead of the carriers ahead of the slur cams.

Other more general aims of the invention are:

a. To minimize the velocities and acceleration of reciprocating masses and thereby permit higher machine speeds.

b. To provide the higher degree of control of the yarn carriers necessary with high machine speeds.

c. To minimize the displacement of the slur cam on any shape of garment and so permit the average speed of the machine to be increased.

If the garment pieces are required to be knitted symmetrically, i.e. with the centers of their varying knitting widths coincident with the centerlines of the knitting heads, then the extents of the axial movements of the two nut housings 2 and 41 must always be equal so that, in the result, the common axis of the spur pinion 12 and the bevel gear 14 remains stationary.

Now the production of fully fashioned garments is accomplished by knitting fronts, backs and sleeves usually in sequence on one straight-bar multihead full-fashioned outerwear machine so that yarns and stitch lengths are compatible in any one garment made up from the garments pieces produced on that machine.

The knitting beds of such machines, as in the illustrated improved machine, are conventionally of such a width as to cater for a body piece, and during the knitting of a sleeve more than half of the width of the knitting head has heretofore been inoperative It is also a fact that the time required to produce garment sleeves is almost as long as that required to produce the wider backs and fronts and represents a considerable proportion of the overall turn round time.

Accordingly, a feature of the present invention resides in the provision, in a multihead straight-bar knitting machine equipped with the herein described draw shortening and asymmetric center differential units, of means enabling two identical sleeves or any other appropriate identical garment pieces to be knitted on each knitting head or division with the object of substantially increasing the overall output of the machine.

The said means comprise a secondary set of slur boxes and slur cams such as SSC (FIG. 6) slidably mounted on the same fixed slur bar or rail 94 (see FIG. 7) but coupled together by a second tie bar 95. During normal knitting of wide or single garment pieces, such as fronts or backs, the secondary slur cams SSC remain stationary and nonfunctional between the knitting heads whilst the primary slur cams PSC are reciprocated in conventional manner by the asymmetrical draw mechanism DM. This draw mechanism enables the slur cams PSC and SSC to be driven over only one-half of the knitting head width. if the secondary slur earns SSC are simply but firmly coupled to the primary slur cams SSC, as for example by a solenoid actuated latch 96 between the two tie bars 63 and 95, the pair of slur cams in each division being pitched apart at a distance of one-half of the knitting bed width, as shown in H6. 6, then it is possible to reciprocate the combined slur cam assembly to sink yarn over two distinct lengths of each knitting bed for the knitting of two separate but identical garment pieces on each bed.

The yarn laying means must in like manner consist of two carrier rods 97 and 98 (F IG. 1), having primary and secondary yarn carriers PC and SC respectively affixed so that each rod has one yarn carrier in each division. During normal knitting of wide garment pieces one carrier rod remains stationary outside the knitting width. But during the knitting of two identical garment pieces on one knitting head, the secondary carrier rod 98 is coupled to the primary carrier rod 97 such that the two yarn carriers PC and SC in each knitting division are pitched apart at a distance of one-half of the knitting bed width. The combined carrier rods are reciprocated in conventional manner, with controlled lead over the slur cams, by the draw mechanism DM. 7

Shaping of the sleeves, i.e. narrowing and widening in the course, would be accomplished by conventional means, the normal main narrowing boxes being associated with the main selvedge screws and therefore corresponding in position for one garment piece on each knitting head and the vee-neck fashioning boxes being correspondingly positioned for the second garment piece on each knitting head.

The system just described lends itself to automatic sequencing during turn round between gannent pieces.

Since in this system the reciprocating masses are increased, it is necessary or at least desirable that the machine be run at a slightly lower speed. However, the output of sleeves would be doubled, and a saving of from 50 percent to 80 percent in the production time of sleeves is expected.

It is considered that FIG. 6 sufficiently illustrates the manner of knitting two identical sleeves SL and SL on each knitting headespecially as many of the reference letters used in this FIG. are the sameas those used in FIG. 1 and thus already referred to earlier in the description.

We claim:

the machine; a sinker head at each division; slur cam boxes fitted with slur cams, one to each division; a tie bar which extends along the length of the machine and couples the slur cam boxes together; at lease one carrier rod which extends the length of the machine; yarn carriers, at least one to each knitting head, mounted upon said carrier rod; a slur drive rack combined with the said tie bar; a carrier drive for moving the carrier rod; a variable draw mechanism including a rotary draw cam, a fulcrummed main draw lever caused to swing by the cam and a draw bar movable to and fro from said lever; gearing means for transmitting reciprocating movements from the draw mechanism both to said carrier drive and to said slur drive rack to impart traverses across said knitting heads and said sinker heads to the yarn carriers and the slur cams with cams, lead of the carriers over the slur cams; L.H. and RH. rotary selvedge screws at the ends of the machine for varying the traverses of the slur cams; and nut housings axially movable along the selvedge screws for limiting the traverses of the carrier rod; the machine being characterized in that it includes a differential movement-transmitting unit comprising oppositely acting components and interposed driving means which are common to both such components and are incorporated into the aforementioned gearing system, and gearing between the L.H. and RH. selvedge screws and the said two components whereby rotations of the said selvedge screws causes proportional movements of the two components to adjust the carrier and slur drives, through the said interposed driving means, so that the varying carrier and slur traverses are asymmetric with respect to the centerlines of the knitting heads, said differential movement-transmitting unit maintaining the central points of said carrier and slur traverses substantially coincident with the centers of the varying knitting widths; a linear draw mechanism having a rectilinearly movable draw bar and a variable die block mounted on the main draw lever for varying the swing of the latter, such mechanism ensuring a substantially constant overtravel of the slur cam traverse with regard to the yarn carrier travel in each division at all knitting widths; a draw shortening differential unit for the purpose of so varying the to and fro movements of the draw bar as to minimize the overtravel of the slur cams beyond the selvedge positions of the yarn carriers, said last mentioned unit comprising first and second differential components, further gear means for gearing said first and second components together and a draw-shortening member which is engaged with one of the said first and second components and is moved whenever the said one component is rotated; additional gearing means located between the L.H. and R.H. selvedge screws and said first and second components for causing proportional rotation of said first and second components responsive to rotation of the selvedge screws; and means connecting the draw-shortening member with the main draw lever so that whenever said member is moved the fulcrum of the main draw lever and hence also the variable die block are correspondingly moved, the output from the draw shortening differential unit thereby algebraically summating the combined rotations of the two selvedge screws.

2. A straight-bar knitting machine according to claim ll, wherein the differential movement transmitting unit comprises two opposite-handed worms and an interposed wormwheel.

3. A straight-bar knitting machine according to claim 2, wherein the said first gearing means includes a pinion which is coaxial with respect to and rotatable together with the wormwheel and is arranged in mesh with a rack coupled to the draw bar of the variable draw mechanism, and wherein the l. A straight-bar knitting machine comprising, in combinasaid worms algebraically summate the axial movements of the nut housings along the selvedge screws so as to influence the rotational axis of the pinion, according to garment shaping requirements, any lateral displacement of the pinion axis effected by rotation of either selvedge screw being proportional to one-half of the axial distance moved by the nut housing along that screw.

4. A straight-bar knitting machine according to claim 2, wherein a transmission shaft coaxial with the wormwheel is mounted in a slipper freely slidable relatively to the worms and the wormwheel is freely centered in the slipper whereby any displacement of this slipper in either direction causes offcentering of the carrier and slur drives.

5. A straight-bar knitting machine according to claim 4, wherein the slipper is slidable along and guided by the opposite-handed worms, and the pinion in mesh with the rack reeiprocated from the variable draw mechanism is secured upon the said transmission shaft.

6. A straight-bar knitting machine according to claim 5, wherein there is also secured upon the said transmission shaft a bevel gear intermeshed with a companion bevel gear which latter gear is slidably engaged with a splined shaft constituting part of the gearing system adapted to convey from the draw mechanism to and fro movements to the carrier drive and the slur drive rack, the said splined shaft permitting all necessary displacements of the slipper slidably along the worms.

7. A straight-bar knitting machine according to claim 1, wherein the draw shortening differential mechanism is in unit form comprising a screw, a splined shaft disposed parallel to said screw and a nut housing engaged with the latter, the said nut housing and the splined shaft having respectively integral therewith two spur gears which are intermeshed, and the screw and the splined shaft being independently rotatable from the two selvedge screws each through the medium of a pair of intermeshed gears.

8. A straight-bar knitting machine according to claim 7, which includes a pivoted lever upon which the swinging main draw lever is fulcrummed, and a connection between said pivoted lever and the nut housing engaged with the screw of the draw shortening differential unit whereby movement of the said nut housing along this screw varies the position of the fulcrum of the main draw lever and hence also the position of a die block can'icd by said draw lever.

9. A straight-bar knitting machine according to claim I, which includes a carrier driving chain and a slur draw chain arranged to travel to and fro together around respective sets of chain sprockets, and an automatically operable lead changeover means for reversing the controlled lead of each yarn carrier over the corresponding slur cam at each reversal of the traverse of the said slur cam across the corresponding sinker head.

10. A straight-bar knitting machine according to claim 1, which includes means enabling two identically shaped garment pieces to be knitted on each knitting head.

11. A straight-bar knitting machine according to claim 10, wherein said enabling means comprise a secondary set of slur boxes and slur earns; a fixed slur bar for the support both of said secondary slur boxes and cams as well as the normally provided slur boxes and slur cams; a second tie bar coupling together said secondary slur boxes and earns, there being one primary slur cam and one secondary slur cam in each division of the machine pitched apart a distance equal to one-half of the knitting bed width; disconnectable means for connecting said second tie bar to a first tie bar serving to couple together the primary slur boxes and slur cams; primary and secondary carrier rods having respectively affixed thereto primary and secondary yarn carriers so that each rod has one carrier in each division; and means for disconnectingly connecting together both rods suchwise that the two carriers in each division are pitched apart a distance equal to one-half of the knitting bed width.

12. A straight-bar knitting machine according to claim 7, wherein the screw of the draw shortening differential unit is driven from the L.H. selvedge screw through the medium of chain and sprocket gearing, a first longitudinal shaft and a pair of intermeshed spiral gears respectively secured to the said first shaft and the differential screw; and the splined shaft of the said unit is similarly driven from the R.H. selvedge screw through the medium of further chain and sprocket gearing, a second longitudinal shaft coaxiall disposed with respect to said first shaft and a second pan 0 intermeshed gears respectively secured to said second shaft and the splined shaft. 

1. A straight-bar knitting machine comprising, in combination, a plurality of knitting heads at corresponding divisions of the machine; a sinker head at each division; slur cam boxes fitted with slur cams, one to each division; a tie bar which extends along the length of the machine and couples the slur cam boxes together; at lease one carrier rod which extends the length of the machine; yarn carriers, at least one to each knitting head, mounted upon said carrier rod; a slur drive rack combined with the said tie bar; a carrier drive for moving the carrier rod; a variable draw mechanism including a rotary draw cam, a fulcrummed main draw lever caused to swing by the cam and a draw bar movable to and fro from said lever; gearing means for transmitting reciprocating movements from the draw mechanism both to said carrier drive and to said slur drive rack to impart traverses across said knitting heads and said sinker heads to the yarn carriers and the slur cams with cams, lead of the carriers over the slur cams; L.H. and R.H. rotary selvedge screws at the ends of the machine for varying the traverses of the slur cams; and nut housings axially movable along the selvedge screws for limiting the traverses of the carrier rod; the machine being characterized in that it includes a differential movementtransmitting unit comprising oppositely acting components and interposed driving means which are common to both such components and are incorporated into the aforementioned gearing system, and gearing between the L.H. and R.H. selvedge screws and the said two components whereby rotations of the said selvedge screws causes proportional movements of the two components to adjust the carrier and slur drives, through the said interposed driving means, so that the varying carrier and slur traverses are asymmetric with respect to the centerlines of the knitting heads, said differential movement-transmitting unit maintaining the central points of said carrier and slur traverses substantially coincident with the centers of the varying knitting widths; a linear draw mechanism having a rectilinearly movable draw bar and a variable die block mounted on the main draw lever for varying the swing of the latter, such mechanism ensuring a substantially constant overtravel of the slur cam traverse with regard to the yarn carrier travel in each division at all knitting widths; a draw shortening differential unit for the purpose of so varying the to and fro movements of the draw bar as to minimize the overtravel of the slur cams beyond the selvedge positions of the yarn carriers, said last mentioned unit comprising first and second differential components, further gear means for gearing said first and second components together and a draw-shortening member which is engaged with one of the said first and second components and is moved whenever the said one component is rotated; additional gearing means located between the L.H. and R.H. selvedge screws and said first and second components for causing proportional rotation of said first and second components responsive to rotation of the selvedge screws; and means connecting the draw-shortening member with the main draw lever so that whenever said member is moved the fulcrum of the main draw lever and hence also the variable die block are correspondingly moved, the output from the draw shortening differential unit thereby algebraically summating the combined rotations of the two selvedge screws.
 2. A straight-bar knitting machine according to claim 1, wherein the differential movement-transmitting unit comprises two opposite-handed worms and an interposed wormwheel.
 3. A straight-bar knitting machine according to claim 2, wherein the said first gearing means includes a pinion which is coaxial with respect to and rotatable together with the wormwheel and is arranged in mesh with a rack coupled to the draw bar of the variable draw mechanism, and wherein the said worms algebraically summate the axial movements of the nut housings alonG the selvedge screws so as to influence the rotational axis of the pinion, according to garment shaping requirements, any lateral displacement of the pinion axis effected by rotation of either selvedge screw being proportional to one-half of the axial distance moved by the nut housing along that screw.
 4. A straight-bar knitting machine according to claim 2, wherein a transmission shaft coaxial with the wormwheel is mounted in a slipper freely slidable relatively to the worms and the wormwheel is freely centered in the slipper whereby any displacement of this slipper in either direction causes offcentering of the carrier and slur drives.
 5. A straight-bar knitting machine according to claim 4, wherein the slipper is slidable along and guided by the opposite-handed worms, and the pinion in mesh with the rack reciprocated from the variable draw mechanism is secured upon the said transmission shaft.
 6. A straight-bar knitting machine according to claim 5, wherein there is also secured upon the said transmission shaft a bevel gear intermeshed with a companion bevel gear which latter gear is slidably engaged with a splined shaft constituting part of the gearing system adapted to convey from the draw mechanism to and fro movements to the carrier drive and the slur drive rack, the said splined shaft permitting all necessary displacements of the slipper slidably along the worms.
 7. A straight-bar knitting machine according to claim 1, wherein the draw shortening differential mechanism is in unit form comprising a screw, a splined shaft disposed parallel to said screw and a nut housing engaged with the latter, the said nut housing and the splined shaft having respectively integral therewith two spur gears which are intermeshed, and the screw and the splined shaft being independently rotatable from the two selvedge screws each through the medium of a pair of intermeshed gears.
 8. A straight-bar knitting machine according to claim 7, which includes a pivoted lever upon which the swinging main draw lever is fulcrummed, and a connection between said pivoted lever and the nut housing engaged with the screw of the draw shortening differential unit whereby movement of the said nut housing along this screw varies the position of the fulcrum of the main draw lever and hence also the position of a die block carried by said draw lever.
 9. A straight-bar knitting machine according to claim 1, which includes a carrier driving chain and a slur draw chain arranged to travel to and fro together around respective sets of chain sprockets, and an automatically operable lead changeover means for reversing the controlled lead of each yarn carrier over the corresponding slur cam at each reversal of the traverse of the said slur cam across the corresponding sinker head.
 10. A straight-bar knitting machine according to claim 1, which includes means enabling two identically shaped garment pieces to be knitted on each knitting head.
 11. A straight-bar knitting machine according to claim 10, wherein said enabling means comprise a secondary set of slur boxes and slur cams; a fixed slur bar for the support both of said secondary slur boxes and cams as well as the normally provided slur boxes and slur cams; a second tie bar coupling together said secondary slur boxes and cams, there being one primary slur cam and one secondary slur cam in each division of the machine pitched apart a distance equal to one-half of the knitting bed width; disconnectable means for connecting said second tie bar to a first tie bar serving to couple together the primary slur boxes and slur cams; primary and secondary carrier rods having respectively affixed thereto primary and secondary yarn carriers so that each rod has one carrier in each division; and means for disconnectingly connecting together both rods suchwise that the two carriers in each division are pitched apart a distance equal to one-half of the knitting bed width.
 12. A straight-bar knitting machine according to claim 7, wherein the screw of tHe draw shortening differential unit is driven from the L.H. selvedge screw through the medium of chain and sprocket gearing, a first longitudinal shaft and a pair of intermeshed spiral gears respectively secured to the said first shaft and the differential screw; and the splined shaft of the said unit is similarly driven from the R.H. selvedge screw through the medium of further chain and sprocket gearing, a second longitudinal shaft coaxially disposed with respect to said first shaft and a second pair of intermeshed gears respectively secured to said second shaft and the splined shaft. 